Scaffold jack



Feb. 6, 1934. E B, SNEAD 1,945,828

SCAFFOLD JACK Filed March 14, 1932 2 Sheets-Sheet l Feb. 6, E. B. SNEAD S CAFFOLD JACK dwf/1. ./head Patented Feb. 6, 1934 UNITED STATES PATENT.' OFFICE This invention relates kto new and useful improvements in scaffold jacks.

One object of the invention is to provide Ian yimproved scaiold jack for use in connection with a hanging scaffold or the like.

A further object of the invention is to provide an improved jack arranged for climbing and descending a Vertical support.

Another object of the invention is to provide le) an improved jack particularly adapted for climbing and descending a suspended cable and involving certain features making for simplicity, ease and certainty of operation, and safety.

Still another object of the invention is to provide a jack including a tubular carrier for receiving a cable or the like and having mounted therein movable means for gripping the cable together with operating elements arranged so that the gripping elements may be stepped longitudinally of the cable and the tubular support thus raised or lowered.

A construction designed to carry out the invention will be hereinafter described together with other features of the invention.

The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawings in which an example of the invention is shown, and wherein:

Figure 1 is a view illustrating a scaold .suspended from one of the oors of a building and equipped with jacks constructed in accordance with the invention,

Figure 2 is a vertical sectional view of the jack with its parts set for lclimbing a cable,

Figure 3'is a. similar view showing the parts 'set for descending a cable,

Figure 4 is an enlarged horizontal crosssectional view taken on the line 4 4 of Figure 2, the coiled springs being omitted for clearness sake, and

` Figure 5 is a detail of one of the latches.

In the drawings the numeral 10 designates a tubular carrier or support which may be made o! metal tubing, piping, or any other structure suitable for the purpose. The pipe 10, intermediate its ends, is provided with diametrically opposite slots 11 and 12. Adjacent the slot 11 and at one side of the vertical center of the pipe a transverse bolt 13 is fastened in the pipe and an operating lever 14 is mounted to pivot on this bolt. The slots are .ot auch lengths as to permit `ample vertical swinging of said lever. The lever has a reduced end 14 for receiving a suitable handle or bar (not shown), so as to give sunlcient leverage for swinging said lever and to be removed when the jack is not in use.

Above the lever cylindrical bushings 15 and 16 constituting gripping members, are slidably mounted in the pipe. The pipeis provided with 00 dametrically opposite slots 17 and the bushings are formed with bosses 18 at their upper ends, which engage in said slots and guide the bushings, as well as holding them against rotation.

It is to be understood that if the member 10 and 05 the bushings were not cylindrical and, therefore, `did not tend to rotate, the bosses 18 would not be needed, and the invention is not to be limited to these parts. The bushings are arranged one above the other and each has an inclined central opening or passage 19 extending therethrough and these passages are inclined in diametrically opposite directions. The supporting cable 20 extends axially through the pipe 10 7 `and .the passages 19.

Each bushing has a vertical slot 21 extending outwardly from its passage 19. In each slot is mounted a triangular dog 22 pivoted on a pin 23 at its upper inner corner and provided with a grooved gripping face 24. These dogs extend 90. outwardly through the slots 17 from opposite sides of 'the bushings. One of the dogs has its outer end pivoted to the upper ends of a pair of long links 25, while the other dog has its outer end pivoted to the upper ends of a pair of 8 5 short links 26'. These links have their lower Aends pivoted on opposite sides of the lever 14 by bolts 27 and 27', which are also on opposite sides o1 the pivot bolt 13.

opposite its pivot 2s each dog has e curved 9 .and grooved gripping nose 28, which coacts with the grooved face '24 in gripping the cable 20 and holding it'against the opposite inclined wall 0f kbuilding and may be fastened by U-bolts 30,

or in any other suitable manner. One Abeam is provided for each pair of cables and ii a scaliold 105 is to be supported two pairs of cables are employed. A pipe 10 is provided for each cable and each pair ci pipes carries a cross 4baat 31 z at their lower ends on which the scaffold boards '32 are supported. Extension pipes 33 have their yto -links and 26 now acting as hangers. 'again elevates the pipe 10 and at the same time .swings the short links 26 upwardly and elevates upper ends telescoped into the upper ends of the pipe 10 and fastened by bolts 34. The extensions 33 carry cross bars 35 on which overhead protecting boards 36 are mounted. Each pipe 10 is equipped with the jack elements.

With the parts as shown in Figure 2, the jack may be elevated on the cable.. Upon the initial upward swing of the end 14 of the lever 14, the lower dog 22 is swung down to grip the cable, as is shown in Figure 2, and immediately thereafter the upper dog is swung to release the cable. Upon further swinging the lever end 14 upwardly, the bolt 27 becomes the fulcrum point,

and, therefore, the bolt 13 is swung with the lever, thereby elevating the pipe 10, which will' raise the scaffold. At the same Jtime the links 25 will swing the upper dog 22 into engagement with the top of the slot 21 of the upperbushing 15, thus sliding said bushing upwardly along the cable. During this entire movement in which the pipe 10 and the bushing 15 are elevated, the lower dog 22 maintains its grip upon the cable, and

the links 26 act as hangers to support the fulcrum '27 and the bolt 13 provides a connection for lifting the pipe 10.

When the lever end 14 reaches the end of its upper stroke froml the position shown in Figure 2, and begins its down stroke, the dogs are swung so that the upper dog 22 now grips the cable 20 and the bolt 27 becomes the iulcrum point, the This `the lower bushing 16. It is pointed out that 'the bolt 13 is not the fulcrum point for the lever but is merely a connection for moving the pipe 10. When the lever end 14' starts its upward swing from the position shown in Figure 2, the fulcrum point is at 13 for a short time until' the lower dog 22 grips the cable; likewise the upper dog 22 does not release the grip on the cable 20 until the lower dog 22 takes hold of said cable; also on the next downward swing of the lever the lower dog does not releaseits grip until the uppery dog grips the cable. This is due to the fact that the released or non-gripping bushingis supbushing are carried downward by the weight/.of

the device. Thus upon the initial upward swinging of the lever end 14', the bolt 13 acts as the fulcrum causing the outer pivot point of the lower any downward movement oi' the pipe 10, which .latter has connection with the outer pivot points ,of the dogs, because of the bolt 13, lever 14 and links 25 and 26 would swing the dogs downwardly to tighten their grips on the cable.

AShould one of the bushings fail to function the :lever would be pulled downwardly on that side which is connected to said bushing until said lever rests on the bottom of the slotrll or 12, thus balancing the pull on theA opposite side of the lever which is connected to the gripping bushing.

j In order that the scaffold may be lowered and -the jack-caused to descend on the cable 20, it is necessary to provide a pair Vof latch bars 37 for the fulcrum 27 ana a similar pair of latch bars 38 for the fulcrum 27. These bars straddle and are pivotally supported by lugs 39 extending from opposite sides of the bushings through the slot 17 and are pivoted on bolts 40. Each pair of bars also straddle the lever 14 and are connected at their lower ends by bolts 41 (Figures 2 and 4). Each bolt 41 is attached to one end of a coiledspring 42 having its upper end pivoted to the lower edge of the lever 14. The bolt 27- i1s keyed in the lever 14 (Figure 2) and has nuts 43 fastened thereon. These nuts are ad- `jacent to the outer sides of the links 26 but are to straddle Vthe links when swung outwardly,'as

shown in Figures 3 and 5. When it is desired to lower ther jack, these bars are sprung so as to be swung outwardly beyond the nuts 43 and 44, as shown in Figures 3 and 5. This will place the springs 42 under. tension so that the slightest movement will cause the bars 37 and 38, together with their respective bushings, to follow said lever. Each bar has a hook (Figure 5) on its inner edge so arranged as to engage under the nuts 43 and 44. It will be seen that when the lever end 14' is in its lowered position, as shown in Figures 3 and 5, thethooks 45 of the latch bars 37 will be in engagement with the nut 43. Due to the particular position of the angular nuts 44 the vhooks 45 of the bars 33 will not engage said nuts,

the spring 42. ported by the spring 42 and latch bars 37 or 38, which will be hereinafter described, while -the pipe 10 and the link 25 or 26 of the released The spring 42 being under tension and secured to the vlever 14 serves to lock the bushing 15 with the upper dog, whereby swinging of the lever'will `tend to raise both the bushing and the dog. But,'

since thel dog is gripping the cable, said dog can not be released until the latch bars 38 are returned to the position shown in Figure 2, or upon `lowering of the bushing. This is dueto the fact that the link 25, bushing l5,.and latchbars 38 are all lockedto eachother and capable' of moving only as a unit, when the spring 42 is under tension, as in Figure 3.

As the lever end 14 swings upwardly, it is seen that the fulcrumV is at the bolt 27. At -this time, the nuts 43 are in engagement with the hooks 45 of the latch bars 37, and continued swinging of the lever causes the bushing 16, to which said bars are secured, and the pipe to be slid downwardly on the cable.. Just before the lever reaches the end Vof itsstroke, the nuts'43, rotating andowing to their angular sides, will disengage from the hooks 45, thereby permitting the lower dog to be swung by the links 26 and grip the cable, and at the end of the stroke the nuts.

44 will engage the hooks of the bars 38. Upon the next downward swing of the lever end' 14 the bolt 27' becomes the fulcrum point because the .latch bar 37 and its spring 42 serve to lock the bushing 16 with relation'to the lower dos 22,-

and the lowering operation is continued through the agency of the latch bars 38.

Various changes in the size and shape of the different parts, as well as modifications and alterations, may be made within the scope of the appended claims.

Having illustrated and described a preferred form of the invention, what I claim, is:

l. In a jack, a carrier, a pair of gripping members slidably mounted in the carrier, a lever pivoted in the carrier, grippers pivoted in the gripping members, and connections between the grippers and the lever pivoted to the lever on opposite sides of itsI pivot for actuating said grippers and sliding said members when said lever is swung.

2, A jack as set forth in claim 1, and latches connected to the gripping members and having means for engaging the pivots of the connections on the lever for reversing the actions of the grippers and the members.

3. In a jack, a carrier, a pair of cable gripping members slidably mounted one above the other in the carrier, a lever pivoted in the carrier, cable grippers pivoted in the gripping members, and connections between the grippers and the lever pivoted to the lever on opposite sides of its pivot for actuating said grippers and sliding said members when said lever is swung.

4. A jack as set forth in claim 3, and latches connected to the gripping members and having means for engaging the pivots of the connections on the lever for reversing the actions of the grippers and the members.

5. In a jack, a carrier, a pair of gripping members slidably mounted in the carrier and having' upright passages therethrough, said members being mounted one above the other, a dog pivoted in each member for gripping a support extending through the passage thereof, and means for actuating the dog of one member and advancing the other member upon one operation and actuating the other dog and advancing the other member upon the next operation.

6. A jack as set forth in claim 5, and means for reversing the direction of travel of the gripping members and the gripping actions of the dogs.

'7. In a jack, an upright carrier, bushings slidable in said carrier one above the other and having upright passages extending therethrough, dogs pivoted in the bushings and co-aoting with the passages thereof for gripping a supporting element passing through said passages, a lever pivoted on the carrier, and links pivoted to the lever on opposite sides of its pivot and also pivoted to the dogs for swinging the same, the dogs being mounted in the bushings so as to slide the same when swung out of gripping relation and propelled by the link attached thereto.

8. A jack as set forth in claim 7, and latches pivoted to the bushings and having means for engaging the pivots of the links on the lever.

9. In a jack, an upright tubular carrier, the carrier having diametrically opposite upper slots and diametrically opposite lower slots, cylindrical bushings slidably mounted in the carrier one above the other and having cable passages extending therethrough, cable gripping dogs pivoted in the bushings for co-acting with the cable passages and extending through the upper slots, a lever pivoted in the carrier and extending through the lower slots, and links pivotally connecting the dogs and the lever.

10. A jack as set forth in claim 9, lugs extending from the bushings through the upper slots, latch bars pivoted at their upper ends to the lugs and straddling the links and lever, coiled springs connecting the latch bars with the lever, nuts fastened on the pivotal connections between the links and the lever, and hooks on the latch bars for engaging the nuts for reversing the travel of the bushings upon operation of the lever.

l1. A jack as set forth in claim l and means connected with the lever and the gripping members for supporting each member when its dog releases the cable.

12. In a jack, an upright carrier, bushings slidable in said carrier one above the other and having upright passages extending therethrough, dogs pivoted in the bushings and coacting with the passages thereof for gripping a supporting element passing through said passages, a lever pivoted on the carrier, links pivoted to the lever on opposite sides of its pivot and also pivoted to the dogs for swinging the same, the dogs being mounted in the bushings so as to slide the same when swung out of gripping relation and propelled by the link attached thereto, latches pivoted to the bushings and having means for engaging the pivot points of the links on the lever, and springs carried by the lever and supporting the latches.

EDWIN B. SNEAD. 

